Previously, there is known a valve device that includes a body, a valve element in a form of a spool, and a seat component in a form of a plate (see, for example, JP446010762).
With reference to FIGS. 5 and 6, a disadvantage of a previously proposed valve device of the above kind will be described. As shown in FIGS. 5 and 6, in the previously proposed valve device 100, a body 101 forms an oil pressure circuit that supplies an oil pressure to each corresponding one of a plurality of friction elements of a transmission of a vehicle, and a valve element 102 is received in a hole 103 of the body 101 in a manner that enables movement of the valve element 102 in an axial direction of the valve element 102. Furthermore, a seat component 104 is bent into an L-shape. A bent end portion 104L of the seat component 104, which is bent in this way, is engaged to the body 101 at an inside of the body 101. Thereby, the seat component 104 is positioned in the inside of the body 101 such that removal of the valve element 102 from the hole 103 of the body 101 toward one side in the axial direction of the valve element 102 is limited by the seat component 104.
The body 101 includes a first body 101A and a second body 101B. The first body 101A has the hole 103. The second body 101B is formed separately from the first body 101A. The first body 101A has a receiving region 105, which is formed as a receiving space and receives the seat component 104. The hole 103 opens to the receiving region 105 on the one side in the axial direction of the valve element 102. Furthermore, the receiving region 105 has two openings 105a, 105b that open to an outside of the first body 101A and are configured to enable insertion of a plate having a plate thickness, which is equal to a plate thickness of the seat component 104, through the first body 101A in a state where a plane of the plate is kept perpendicular to the axial direction of the valve element 102. These openings 105a, 105b of the receiving region 105 are opposed to each other in a direction perpendicular to the axial direction of the valve element 102.
The seat component 104 is inserted into the receiving region 105 such that a distal end portion 104T of the seat component 104, which is opposite from the bent end portion 104L, is first inserted into the opening 105a until the distal end portion 104T reaches the opening 105b. Then, the opening 105a is covered with the second body 101B. At this time, a base of the bent end portion 104L, at which the bent end portion 104L is bent relative to the rest of the seat component 104, is engaged to a specific portion 105as of the first body 101A, which forms the opening 105a. Because of this engagement of the bent end portion 104L, removal (detachment) of the seat component 104 from the receiving region 105 is limited. Furthermore, the seat component 104 functions as a spring seat for a spring 106 that urges the valve element 102 toward the other side in the axial direction of the valve element 102.
However, in the above construction, there is a possibility of that the bent end portion 104L is urged against the specific portion 105as to cause tilting of the seat component 104. When the seat component 104 is tilted, the valve element 102 makes a one-sided contact with the seat component 104. As an example of the one-sided contact, FIG. 5 shows a state where a lower portion of the valve element 102 makes a contact with the seat component 104 while an upper portion of the valve element 102 is spaced from the seat component 104.
In view of the above disadvantage, there is disclosed a seat component, in which both of a front surface and a back surface of the seat component are formed as planar surfaces, respectively, which are parallel to each other without bending the seat component into the L-shape while the seat component has a projection that projects in a direction parallel to the planar surfaces of the seat component in a plan view of the seat component, and a side edge of the projection is engaged to the body to limit the removal (detachment) of the seat component (see, for example, JP2006-300197A).
However, in the valve device of JP2006-300197A, although the removal (detachment) of the seat component can be limited, the seat component is movable in a direction parallel to the plane of the seat component in the receiving region, and thereby the position of the seat component is not stable. Furthermore, when the position of the spring is deviated in response to the movement of the seat component, an output characteristic of the valve device may possibly be changed, and/or wearing of a wall surface of a receiving region of the valve element, which receives the spring, may possibly occur due to buckling of the spring.
Therefore, there is a demand for a structure that can limit movement of a seat component in a direction parallel to a plane of the seat component while limiting removal (detachment) of the seat component.